Can't activate childtheme for pinboard

During the circumstances if you change an original theme and lost all modifications after an update, I’ve tried to make an child theme of pinboard using this code at my style.css;

@charset "utf-8";
/*
Theme Name: mytheme2013
Version: 1.0
Author: Marcus
Template: pinboard
Theme URI: https://www.onedesigns.com/wordpress-themes/pinboard

License: GNU General Public License v2.0
License URI: license.txt
*/

@import url("../pinboard/style.css");

The strange thing is, that on my local wordpress installation (xampp) the message appears, that my child theme needs the parent theme pinboard, but I can activate it by the backend.

But as I tried to make a testrun on my webinstallation, the message apears that the pinboard theme ist broken and the childtheme was deactivated.

First I thougt it would be an plugin, so I deaktivated all plugins, but that did’nt solve it.

Did I miss something? I can’t understand what I’ve made wrong.

Oh yes I forgot;
The parent theme pinboard is installed. ??